chore(3p/abseil_cpp): unvendor abseil_cpp r/3786

we weren't actually using these sources anymore, okay?

Change-Id: If701571d9716de308d3512e1eb22c35db0877a66
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5248
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: tazjin <tazjin@tvl.su>

1 files changed, 0 insertions, 769 deletions

diff --git a/third_party/abseil_cpp/absl/container/btree_map.h b/third_party/abseil_cpp/absl/container/btree_map.h
deleted file mode 100644
index abc09b0ac068..000000000000
--- a/third_party/abseil_cpp/absl/container/btree_map.h
+++ /dev/null
@@ -1,769 +0,0 @@
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// -----------------------------------------------------------------------------
-// File: btree_map.h
-// -----------------------------------------------------------------------------
-//
-// This header file defines B-tree maps: sorted associative containers mapping
-// keys to values.
-//
-//     * `absl::btree_map<>`
-//     * `absl::btree_multimap<>`
-//
-// These B-tree types are similar to the corresponding types in the STL
-// (`std::map` and `std::multimap`) and generally conform to the STL interfaces
-// of those types. However, because they are implemented using B-trees, they
-// are more efficient in most situations.
-//
-// Unlike `std::map` and `std::multimap`, which are commonly implemented using
-// red-black tree nodes, B-tree maps use more generic B-tree nodes able to hold
-// multiple values per node. Holding multiple values per node often makes
-// B-tree maps perform better than their `std::map` counterparts, because
-// multiple entries can be checked within the same cache hit.
-//
-// However, these types should not be considered drop-in replacements for
-// `std::map` and `std::multimap` as there are some API differences, which are
-// noted in this header file.
-//
-// Importantly, insertions and deletions may invalidate outstanding iterators,
-// pointers, and references to elements. Such invalidations are typically only
-// an issue if insertion and deletion operations are interleaved with the use of
-// more than one iterator, pointer, or reference simultaneously. For this
-// reason, `insert()` and `erase()` return a valid iterator at the current
-// position.
-
-#ifndef ABSL_CONTAINER_BTREE_MAP_H_
-#define ABSL_CONTAINER_BTREE_MAP_H_
-
-#include "absl/container/internal/btree.h"  // IWYU pragma: export
-#include "absl/container/internal/btree_container.h"  // IWYU pragma: export
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-
-// absl::btree_map<>
-//
-// An `absl::btree_map<K, V>` is an ordered associative container of
-// unique keys and associated values designed to be a more efficient replacement
-// for `std::map` (in most cases).
-//
-// Keys are sorted using an (optional) comparison function, which defaults to
-// `std::less<K>`.
-//
-// An `absl::btree_map<K, V>` uses a default allocator of
-// `std::allocator<std::pair<const K, V>>` to allocate (and deallocate)
-// nodes, and construct and destruct values within those nodes. You may
-// instead specify a custom allocator `A` (which in turn requires specifying a
-// custom comparator `C`) as in `absl::btree_map<K, V, C, A>`.
-//
-template <typename Key, typename Value, typename Compare = std::less<Key>,
-          typename Alloc = std::allocator<std::pair<const Key, Value>>>
-class btree_map
-    : public container_internal::btree_map_container<
-          container_internal::btree<container_internal::map_params<
-              Key, Value, Compare, Alloc, /*TargetNodeSize=*/256,
-              /*Multi=*/false>>> {
-  using Base = typename btree_map::btree_map_container;
-
- public:
-  // Constructors and Assignment Operators
-  //
-  // A `btree_map` supports the same overload set as `std::map`
-  // for construction and assignment:
-  //
-  // * Default constructor
-  //
-  //   absl::btree_map<int, std::string> map1;
-  //
-  // * Initializer List constructor
-  //
-  //   absl::btree_map<int, std::string> map2 =
-  //       {{1, "huey"}, {2, "dewey"}, {3, "louie"},};
-  //
-  // * Copy constructor
-  //
-  //   absl::btree_map<int, std::string> map3(map2);
-  //
-  // * Copy assignment operator
-  //
-  //  absl::btree_map<int, std::string> map4;
-  //  map4 = map3;
-  //
-  // * Move constructor
-  //
-  //   // Move is guaranteed efficient
-  //   absl::btree_map<int, std::string> map5(std::move(map4));
-  //
-  // * Move assignment operator
-  //
-  //   // May be efficient if allocators are compatible
-  //   absl::btree_map<int, std::string> map6;
-  //   map6 = std::move(map5);
-  //
-  // * Range constructor
-  //
-  //   std::vector<std::pair<int, std::string>> v = {{1, "a"}, {2, "b"}};
-  //   absl::btree_map<int, std::string> map7(v.begin(), v.end());
-  btree_map() {}
-  using Base::Base;
-
-  // btree_map::begin()
-  //
-  // Returns an iterator to the beginning of the `btree_map`.
-  using Base::begin;
-
-  // btree_map::cbegin()
-  //
-  // Returns a const iterator to the beginning of the `btree_map`.
-  using Base::cbegin;
-
-  // btree_map::end()
-  //
-  // Returns an iterator to the end of the `btree_map`.
-  using Base::end;
-
-  // btree_map::cend()
-  //
-  // Returns a const iterator to the end of the `btree_map`.
-  using Base::cend;
-
-  // btree_map::empty()
-  //
-  // Returns whether or not the `btree_map` is empty.
-  using Base::empty;
-
-  // btree_map::max_size()
-  //
-  // Returns the largest theoretical possible number of elements within a
-  // `btree_map` under current memory constraints. This value can be thought
-  // of as the largest value of `std::distance(begin(), end())` for a
-  // `btree_map<Key, T>`.
-  using Base::max_size;
-
-  // btree_map::size()
-  //
-  // Returns the number of elements currently within the `btree_map`.
-  using Base::size;
-
-  // btree_map::clear()
-  //
-  // Removes all elements from the `btree_map`. Invalidates any references,
-  // pointers, or iterators referring to contained elements.
-  using Base::clear;
-
-  // btree_map::erase()
-  //
-  // Erases elements within the `btree_map`. If an erase occurs, any references,
-  // pointers, or iterators are invalidated.
-  // Overloads are listed below.
-  //
-  // iterator erase(iterator position):
-  // iterator erase(const_iterator position):
-  //
-  //   Erases the element at `position` of the `btree_map`, returning
-  //   the iterator pointing to the element after the one that was erased
-  //   (or end() if none exists).
-  //
-  // iterator erase(const_iterator first, const_iterator last):
-  //
-  //   Erases the elements in the open interval [`first`, `last`), returning
-  //   the iterator pointing to the element after the interval that was erased
-  //   (or end() if none exists).
-  //
-  // template <typename K> size_type erase(const K& key):
-  //
-  //   Erases the element with the matching key, if it exists, returning the
-  //   number of elements erased (0 or 1).
-  using Base::erase;
-
-  // btree_map::insert()
-  //
-  // Inserts an element of the specified value into the `btree_map`,
-  // returning an iterator pointing to the newly inserted element, provided that
-  // an element with the given key does not already exist. If an insertion
-  // occurs, any references, pointers, or iterators are invalidated.
-  // Overloads are listed below.
-  //
-  // std::pair<iterator,bool> insert(const value_type& value):
-  //
-  //   Inserts a value into the `btree_map`. Returns a pair consisting of an
-  //   iterator to the inserted element (or to the element that prevented the
-  //   insertion) and a bool denoting whether the insertion took place.
-  //
-  // std::pair<iterator,bool> insert(value_type&& value):
-  //
-  //   Inserts a moveable value into the `btree_map`. Returns a pair
-  //   consisting of an iterator to the inserted element (or to the element that
-  //   prevented the insertion) and a bool denoting whether the insertion took
-  //   place.
-  //
-  // iterator insert(const_iterator hint, const value_type& value):
-  // iterator insert(const_iterator hint, value_type&& value):
-  //
-  //   Inserts a value, using the position of `hint` as a non-binding suggestion
-  //   for where to begin the insertion search. Returns an iterator to the
-  //   inserted element, or to the existing element that prevented the
-  //   insertion.
-  //
-  // void insert(InputIterator first, InputIterator last):
-  //
-  //   Inserts a range of values [`first`, `last`).
-  //
-  // void insert(std::initializer_list<init_type> ilist):
-  //
-  //   Inserts the elements within the initializer list `ilist`.
-  using Base::insert;
-
-  // btree_map::insert_or_assign()
-  //
-  // Inserts an element of the specified value into the `btree_map` provided
-  // that a value with the given key does not already exist, or replaces the
-  // corresponding mapped type with the forwarded `obj` argument if a key for
-  // that value already exists, returning an iterator pointing to the newly
-  // inserted element. Overloads are listed below.
-  //
-  // pair<iterator, bool> insert_or_assign(const key_type& k, M&& obj):
-  // pair<iterator, bool> insert_or_assign(key_type&& k, M&& obj):
-  //
-  //   Inserts/Assigns (or moves) the element of the specified key into the
-  //   `btree_map`. If the returned bool is true, insertion took place, and if
-  //   it's false, assignment took place.
-  //
-  // iterator insert_or_assign(const_iterator hint,
-  //                           const key_type& k, M&& obj):
-  // iterator insert_or_assign(const_iterator hint, key_type&& k, M&& obj):
-  //
-  //   Inserts/Assigns (or moves) the element of the specified key into the
-  //   `btree_map` using the position of `hint` as a non-binding suggestion
-  //   for where to begin the insertion search.
-  using Base::insert_or_assign;
-
-  // btree_map::emplace()
-  //
-  // Inserts an element of the specified value by constructing it in-place
-  // within the `btree_map`, provided that no element with the given key
-  // already exists.
-  //
-  // The element may be constructed even if there already is an element with the
-  // key in the container, in which case the newly constructed element will be
-  // destroyed immediately. Prefer `try_emplace()` unless your key is not
-  // copyable or moveable.
-  //
-  // If an insertion occurs, any references, pointers, or iterators are
-  // invalidated.
-  using Base::emplace;
-
-  // btree_map::emplace_hint()
-  //
-  // Inserts an element of the specified value by constructing it in-place
-  // within the `btree_map`, using the position of `hint` as a non-binding
-  // suggestion for where to begin the insertion search, and only inserts
-  // provided that no element with the given key already exists.
-  //
-  // The element may be constructed even if there already is an element with the
-  // key in the container, in which case the newly constructed element will be
-  // destroyed immediately. Prefer `try_emplace()` unless your key is not
-  // copyable or moveable.
-  //
-  // If an insertion occurs, any references, pointers, or iterators are
-  // invalidated.
-  using Base::emplace_hint;
-
-  // btree_map::try_emplace()
-  //
-  // Inserts an element of the specified value by constructing it in-place
-  // within the `btree_map`, provided that no element with the given key
-  // already exists. Unlike `emplace()`, if an element with the given key
-  // already exists, we guarantee that no element is constructed.
-  //
-  // If an insertion occurs, any references, pointers, or iterators are
-  // invalidated.
-  //
-  // Overloads are listed below.
-  //
-  //   std::pair<iterator, bool> try_emplace(const key_type& k, Args&&... args):
-  //   std::pair<iterator, bool> try_emplace(key_type&& k, Args&&... args):
-  //
-  // Inserts (via copy or move) the element of the specified key into the
-  // `btree_map`.
-  //
-  //   iterator try_emplace(const_iterator hint,
-  //                        const key_type& k, Args&&... args):
-  //   iterator try_emplace(const_iterator hint, key_type&& k, Args&&... args):
-  //
-  // Inserts (via copy or move) the element of the specified key into the
-  // `btree_map` using the position of `hint` as a non-binding suggestion
-  // for where to begin the insertion search.
-  using Base::try_emplace;
-
-  // btree_map::extract()
-  //
-  // Extracts the indicated element, erasing it in the process, and returns it
-  // as a C++17-compatible node handle. Overloads are listed below.
-  //
-  // node_type extract(const_iterator position):
-  //
-  //   Extracts the element at the indicated position and returns a node handle
-  //   owning that extracted data.
-  //
-  // template <typename K> node_type extract(const K& k):
-  //
-  //   Extracts the element with the key matching the passed key value and
-  //   returns a node handle owning that extracted data. If the `btree_map`
-  //   does not contain an element with a matching key, this function returns an
-  //   empty node handle.
-  //
-  // NOTE: when compiled in an earlier version of C++ than C++17,
-  // `node_type::key()` returns a const reference to the key instead of a
-  // mutable reference. We cannot safely return a mutable reference without
-  // std::launder (which is not available before C++17).
-  //
-  // NOTE: In this context, `node_type` refers to the C++17 concept of a
-  // move-only type that owns and provides access to the elements in associative
-  // containers (https://en.cppreference.com/w/cpp/container/node_handle).
-  // It does NOT refer to the data layout of the underlying btree.
-  using Base::extract;
-
-  // btree_map::merge()
-  //
-  // Extracts elements from a given `source` btree_map into this
-  // `btree_map`. If the destination `btree_map` already contains an
-  // element with an equivalent key, that element is not extracted.
-  using Base::merge;
-
-  // btree_map::swap(btree_map& other)
-  //
-  // Exchanges the contents of this `btree_map` with those of the `other`
-  // btree_map, avoiding invocation of any move, copy, or swap operations on
-  // individual elements.
-  //
-  // All iterators and references on the `btree_map` remain valid, excepting
-  // for the past-the-end iterator, which is invalidated.
-  using Base::swap;
-
-  // btree_map::at()
-  //
-  // Returns a reference to the mapped value of the element with key equivalent
-  // to the passed key.
-  using Base::at;
-
-  // btree_map::contains()
-  //
-  // template <typename K> bool contains(const K& key) const:
-  //
-  // Determines whether an element comparing equal to the given `key` exists
-  // within the `btree_map`, returning `true` if so or `false` otherwise.
-  //
-  // Supports heterogeneous lookup, provided that the map is provided a
-  // compatible heterogeneous comparator.
-  using Base::contains;
-
-  // btree_map::count()
-  //
-  // template <typename K> size_type count(const K& key) const:
-  //
-  // Returns the number of elements comparing equal to the given `key` within
-  // the `btree_map`. Note that this function will return either `1` or `0`
-  // since duplicate elements are not allowed within a `btree_map`.
-  //
-  // Supports heterogeneous lookup, provided that the map is provided a
-  // compatible heterogeneous comparator.
-  using Base::count;
-
-  // btree_map::equal_range()
-  //
-  // Returns a closed range [first, last], defined by a `std::pair` of two
-  // iterators, containing all elements with the passed key in the
-  // `btree_map`.
-  using Base::equal_range;
-
-  // btree_map::find()
-  //
-  // template <typename K> iterator find(const K& key):
-  // template <typename K> const_iterator find(const K& key) const:
-  //
-  // Finds an element with the passed `key` within the `btree_map`.
-  //
-  // Supports heterogeneous lookup, provided that the map is provided a
-  // compatible heterogeneous comparator.
-  using Base::find;
-
-  // btree_map::operator[]()
-  //
-  // Returns a reference to the value mapped to the passed key within the
-  // `btree_map`, performing an `insert()` if the key does not already
-  // exist.
-  //
-  // If an insertion occurs, any references, pointers, or iterators are
-  // invalidated. Otherwise iterators are not affected and references are not
-  // invalidated. Overloads are listed below.
-  //
-  // T& operator[](key_type&& key):
-  // T& operator[](const key_type& key):
-  //
-  //   Inserts a value_type object constructed in-place if the element with the
-  //   given key does not exist.
-  using Base::operator[];
-
-  // btree_map::get_allocator()
-  //
-  // Returns the allocator function associated with this `btree_map`.
-  using Base::get_allocator;
-
-  // btree_map::key_comp();
-  //
-  // Returns the key comparator associated with this `btree_map`.
-  using Base::key_comp;
-
-  // btree_map::value_comp();
-  //
-  // Returns the value comparator associated with this `btree_map`.
-  using Base::value_comp;
-};
-
-// absl::swap(absl::btree_map<>, absl::btree_map<>)
-//
-// Swaps the contents of two `absl::btree_map` containers.
-template <typename K, typename V, typename C, typename A>
-void swap(btree_map<K, V, C, A> &x, btree_map<K, V, C, A> &y) {
-  return x.swap(y);
-}
-
-// absl::erase_if(absl::btree_map<>, Pred)
-//
-// Erases all elements that satisfy the predicate pred from the container.
-template <typename K, typename V, typename C, typename A, typename Pred>
-void erase_if(btree_map<K, V, C, A> &map, Pred pred) {
-  for (auto it = map.begin(); it != map.end();) {
-    if (pred(*it)) {
-      it = map.erase(it);
-    } else {
-      ++it;
-    }
-  }
-}
-
-// absl::btree_multimap
-//
-// An `absl::btree_multimap<K, V>` is an ordered associative container of
-// keys and associated values designed to be a more efficient replacement for
-// `std::multimap` (in most cases). Unlike `absl::btree_map`, a B-tree multimap
-// allows multiple elements with equivalent keys.
-//
-// Keys are sorted using an (optional) comparison function, which defaults to
-// `std::less<K>`.
-//
-// An `absl::btree_multimap<K, V>` uses a default allocator of
-// `std::allocator<std::pair<const K, V>>` to allocate (and deallocate)
-// nodes, and construct and destruct values within those nodes. You may
-// instead specify a custom allocator `A` (which in turn requires specifying a
-// custom comparator `C`) as in `absl::btree_multimap<K, V, C, A>`.
-//
-template <typename Key, typename Value, typename Compare = std::less<Key>,
-          typename Alloc = std::allocator<std::pair<const Key, Value>>>
-class btree_multimap
-    : public container_internal::btree_multimap_container<
-          container_internal::btree<container_internal::map_params<
-              Key, Value, Compare, Alloc, /*TargetNodeSize=*/256,
-              /*Multi=*/true>>> {
-  using Base = typename btree_multimap::btree_multimap_container;
-
- public:
-  // Constructors and Assignment Operators
-  //
-  // A `btree_multimap` supports the same overload set as `std::multimap`
-  // for construction and assignment:
-  //
-  // * Default constructor
-  //
-  //   absl::btree_multimap<int, std::string> map1;
-  //
-  // * Initializer List constructor
-  //
-  //   absl::btree_multimap<int, std::string> map2 =
-  //       {{1, "huey"}, {2, "dewey"}, {3, "louie"},};
-  //
-  // * Copy constructor
-  //
-  //   absl::btree_multimap<int, std::string> map3(map2);
-  //
-  // * Copy assignment operator
-  //
-  //  absl::btree_multimap<int, std::string> map4;
-  //  map4 = map3;
-  //
-  // * Move constructor
-  //
-  //   // Move is guaranteed efficient
-  //   absl::btree_multimap<int, std::string> map5(std::move(map4));
-  //
-  // * Move assignment operator
-  //
-  //   // May be efficient if allocators are compatible
-  //   absl::btree_multimap<int, std::string> map6;
-  //   map6 = std::move(map5);
-  //
-  // * Range constructor
-  //
-  //   std::vector<std::pair<int, std::string>> v = {{1, "a"}, {2, "b"}};
-  //   absl::btree_multimap<int, std::string> map7(v.begin(), v.end());
-  btree_multimap() {}
-  using Base::Base;
-
-  // btree_multimap::begin()
-  //
-  // Returns an iterator to the beginning of the `btree_multimap`.
-  using Base::begin;
-
-  // btree_multimap::cbegin()
-  //
-  // Returns a const iterator to the beginning of the `btree_multimap`.
-  using Base::cbegin;
-
-  // btree_multimap::end()
-  //
-  // Returns an iterator to the end of the `btree_multimap`.
-  using Base::end;
-
-  // btree_multimap::cend()
-  //
-  // Returns a const iterator to the end of the `btree_multimap`.
-  using Base::cend;
-
-  // btree_multimap::empty()
-  //
-  // Returns whether or not the `btree_multimap` is empty.
-  using Base::empty;
-
-  // btree_multimap::max_size()
-  //
-  // Returns the largest theoretical possible number of elements within a
-  // `btree_multimap` under current memory constraints. This value can be
-  // thought of as the largest value of `std::distance(begin(), end())` for a
-  // `btree_multimap<Key, T>`.
-  using Base::max_size;
-
-  // btree_multimap::size()
-  //
-  // Returns the number of elements currently within the `btree_multimap`.
-  using Base::size;
-
-  // btree_multimap::clear()
-  //
-  // Removes all elements from the `btree_multimap`. Invalidates any references,
-  // pointers, or iterators referring to contained elements.
-  using Base::clear;
-
-  // btree_multimap::erase()
-  //
-  // Erases elements within the `btree_multimap`. If an erase occurs, any
-  // references, pointers, or iterators are invalidated.
-  // Overloads are listed below.
-  //
-  // iterator erase(iterator position):
-  // iterator erase(const_iterator position):
-  //
-  //   Erases the element at `position` of the `btree_multimap`, returning
-  //   the iterator pointing to the element after the one that was erased
-  //   (or end() if none exists).
-  //
-  // iterator erase(const_iterator first, const_iterator last):
-  //
-  //   Erases the elements in the open interval [`first`, `last`), returning
-  //   the iterator pointing to the element after the interval that was erased
-  //   (or end() if none exists).
-  //
-  // template <typename K> size_type erase(const K& key):
-  //
-  //   Erases the elements matching the key, if any exist, returning the
-  //   number of elements erased.
-  using Base::erase;
-
-  // btree_multimap::insert()
-  //
-  // Inserts an element of the specified value into the `btree_multimap`,
-  // returning an iterator pointing to the newly inserted element.
-  // Any references, pointers, or iterators are invalidated.  Overloads are
-  // listed below.
-  //
-  // iterator insert(const value_type& value):
-  //
-  //   Inserts a value into the `btree_multimap`, returning an iterator to the
-  //   inserted element.
-  //
-  // iterator insert(value_type&& value):
-  //
-  //   Inserts a moveable value into the `btree_multimap`, returning an iterator
-  //   to the inserted element.
-  //
-  // iterator insert(const_iterator hint, const value_type& value):
-  // iterator insert(const_iterator hint, value_type&& value):
-  //
-  //   Inserts a value, using the position of `hint` as a non-binding suggestion
-  //   for where to begin the insertion search. Returns an iterator to the
-  //   inserted element.
-  //
-  // void insert(InputIterator first, InputIterator last):
-  //
-  //   Inserts a range of values [`first`, `last`).
-  //
-  // void insert(std::initializer_list<init_type> ilist):
-  //
-  //   Inserts the elements within the initializer list `ilist`.
-  using Base::insert;
-
-  // btree_multimap::emplace()
-  //
-  // Inserts an element of the specified value by constructing it in-place
-  // within the `btree_multimap`. Any references, pointers, or iterators are
-  // invalidated.
-  using Base::emplace;
-
-  // btree_multimap::emplace_hint()
-  //
-  // Inserts an element of the specified value by constructing it in-place
-  // within the `btree_multimap`, using the position of `hint` as a non-binding
-  // suggestion for where to begin the insertion search.
-  //
-  // Any references, pointers, or iterators are invalidated.
-  using Base::emplace_hint;
-
-  // btree_multimap::extract()
-  //
-  // Extracts the indicated element, erasing it in the process, and returns it
-  // as a C++17-compatible node handle. Overloads are listed below.
-  //
-  // node_type extract(const_iterator position):
-  //
-  //   Extracts the element at the indicated position and returns a node handle
-  //   owning that extracted data.
-  //
-  // template <typename K> node_type extract(const K& k):
-  //
-  //   Extracts the element with the key matching the passed key value and
-  //   returns a node handle owning that extracted data. If the `btree_multimap`
-  //   does not contain an element with a matching key, this function returns an
-  //   empty node handle.
-  //
-  // NOTE: when compiled in an earlier version of C++ than C++17,
-  // `node_type::key()` returns a const reference to the key instead of a
-  // mutable reference. We cannot safely return a mutable reference without
-  // std::launder (which is not available before C++17).
-  //
-  // NOTE: In this context, `node_type` refers to the C++17 concept of a
-  // move-only type that owns and provides access to the elements in associative
-  // containers (https://en.cppreference.com/w/cpp/container/node_handle).
-  // It does NOT refer to the data layout of the underlying btree.
-  using Base::extract;
-
-  // btree_multimap::merge()
-  //
-  // Extracts elements from a given `source` btree_multimap into this
-  // `btree_multimap`. If the destination `btree_multimap` already contains an
-  // element with an equivalent key, that element is not extracted.
-  using Base::merge;
-
-  // btree_multimap::swap(btree_multimap& other)
-  //
-  // Exchanges the contents of this `btree_multimap` with those of the `other`
-  // btree_multimap, avoiding invocation of any move, copy, or swap operations
-  // on individual elements.
-  //
-  // All iterators and references on the `btree_multimap` remain valid,
-  // excepting for the past-the-end iterator, which is invalidated.
-  using Base::swap;
-
-  // btree_multimap::contains()
-  //
-  // template <typename K> bool contains(const K& key) const:
-  //
-  // Determines whether an element comparing equal to the given `key` exists
-  // within the `btree_multimap`, returning `true` if so or `false` otherwise.
-  //
-  // Supports heterogeneous lookup, provided that the map is provided a
-  // compatible heterogeneous comparator.
-  using Base::contains;
-
-  // btree_multimap::count()
-  //
-  // template <typename K> size_type count(const K& key) const:
-  //
-  // Returns the number of elements comparing equal to the given `key` within
-  // the `btree_multimap`.
-  //
-  // Supports heterogeneous lookup, provided that the map is provided a
-  // compatible heterogeneous comparator.
-  using Base::count;
-
-  // btree_multimap::equal_range()
-  //
-  // Returns a closed range [first, last], defined by a `std::pair` of two
-  // iterators, containing all elements with the passed key in the
-  // `btree_multimap`.
-  using Base::equal_range;
-
-  // btree_multimap::find()
-  //
-  // template <typename K> iterator find(const K& key):
-  // template <typename K> const_iterator find(const K& key) const:
-  //
-  // Finds an element with the passed `key` within the `btree_multimap`.
-  //
-  // Supports heterogeneous lookup, provided that the map is provided a
-  // compatible heterogeneous comparator.
-  using Base::find;
-
-  // btree_multimap::get_allocator()
-  //
-  // Returns the allocator function associated with this `btree_multimap`.
-  using Base::get_allocator;
-
-  // btree_multimap::key_comp();
-  //
-  // Returns the key comparator associated with this `btree_multimap`.
-  using Base::key_comp;
-
-  // btree_multimap::value_comp();
-  //
-  // Returns the value comparator associated with this `btree_multimap`.
-  using Base::value_comp;
-};
-
-// absl::swap(absl::btree_multimap<>, absl::btree_multimap<>)
-//
-// Swaps the contents of two `absl::btree_multimap` containers.
-template <typename K, typename V, typename C, typename A>
-void swap(btree_multimap<K, V, C, A> &x, btree_multimap<K, V, C, A> &y) {
-  return x.swap(y);
-}
-
-// absl::erase_if(absl::btree_multimap<>, Pred)
-//
-// Erases all elements that satisfy the predicate pred from the container.
-template <typename K, typename V, typename C, typename A, typename Pred>
-void erase_if(btree_multimap<K, V, C, A> &map, Pred pred) {
-  for (auto it = map.begin(); it != map.end();) {
-    if (pred(*it)) {
-      it = map.erase(it);
-    } else {
-      ++it;
-    }
-  }
-}
-
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_CONTAINER_BTREE_MAP_H_